Very nice to listen to, but I have a few points of (hopefully constructive) criticism
First things first, in my opinion lose the rain backing completely. It's nice and it has a cool effect, but having it there just completely limits how the piece can be used. Plus, you want people to like the piece for what it is without necessarily having to make it seem more ambient. Besides, most people here know about rainymood to be able to add the sound in themselves if they'd like.
So onto the piece itself. Brilliant chord structure, nice instrumentation, nice atmosphere and layering. I think the two areas where it was let down a bit however was the form and the melody.
I always feel a bit harsh saying this, but when a piece gets submitted as a jazz or pop song I always try to judge the piece relative to a proper song, as opposed to merely as background music, which I think is what you've mainly achieved.
Most songs fit a general format of "Intro, verse, chorus, verse, chorus, bridge, chorus"
This piece has a form more like "Intro, chorus, chorus, chorus, chorus, chorus," with each successive chorus being slightly more thickly layered.
What this means, is for the listener the piece gets a bit repetitive. What you've done at 1:42 is the right sort of idea; it creates interest and makes the listener want to keep listening. I think though that you could probably bring this out a bit more and extend it - change the time signature or key or whatever completely if you have to.
The other thing is the melody. The melody is what you can essentially sing along to (regardless of whether it's a vocal part or not). Really, if you tried singing along to this, you couldn't, because well, there isn't a melody. It's completely up to you whether you want to go and actually include a singable melody line, but for this to become a proper song and more than just background music, it's somewhat crucial.
It's not really easy going back and completely changing up so much of the song, but if you can write this in an hour, surely you're capable of extending this into a proper, catchy song. I would like to see this worked on some more though, theres a lot of potential but it's just not QUITE there yet from a musical standpoint.